Is offsite the way to go for affordable housing?

There has been a lot of buzz about so-called prefabs recently, with various reports calling for enhanced use of offsite construction to speed up housing delivery. Key advantages of timber offsite construction include proven performance, reduced costs both on associations’ and residents’ sides, and faster asset value. With financial and political support for accelerated construction, this is a route worth investigating for development teams, asset and finance managers alike.

Proven performance and new possibilities

Offsite construction is a proven feature of millions of affordable new homes in the UK – it’s quick to build without compromising quality. Timber construction accounts for more than 25% of all dwellings in the UK.

Timber is a natural, renewable, and sustainable building material. Engineered timber also embodies all these environmental benefits. Just one of the reasons why the use of cross-laminated timber (CLT) as a structural system is one of the fastest-growing construction methods in many parts of Europe and Asia.

Advances in timber technology have resulted in its use for multi-storey buildings such as Bridport House, a social housing scheme in Hackney, assembled in just 10 weeks.

Reducing costs and creating faster asset value

While broadly cost comparative with traditional building methods, the build times for timber construction are up to 30% faster than for other materials. Such fast construction reduces time onsite and the disruption this causes to a local area, speeds up practical completion and handover, and enables an earlier rental income stream.

Research into offsite construction shows that costs can be more carefully controlled, waste is reduced by up to 90% and fewer defects helps to reduce snagging costs by up to 80%.

Offsite construction is also safer, reducing the risk of onsite worker injury by up to 80%.

Reducing fuel poverty

Timber offsite construction is one of the most energy efficient methods of building homes, using a material with negative carbon emissions and low embodied carbon. Timber products in the built environment lead the way in terms of lifecycle assessment and Environmental Product Declarations. Building with timber can reduce energy bills by 90%.

Timber offsite construction enables significant thermal efficiency, with operational energy costs kept to a minimum. Offsite designers can also better incorporate renewable energy solutions such as ground-source heat pumps and heat recovery ventilation from the start, which can lead to further dramatic reductions in fuel bills to housing associations’ tenants.

Financial and political support for accelerated construction

Mortgage funding and new build warranties are readily provided to timber offsite construction housing developments. BOPAS (Build Offsite Property Assurance Scheme) provides assurance to the lending community on homes constructed using innovative methods that they will deliver consistent performance of a determined durability of at least 60 years.

The Government is committed to supporting accelerated construction: "Offsite construction provides a huge opportunity to increase housing supply and we want to see more innovation like this across the housebuilding sector,” says Gavin Barwell, housing minister.

Housing associations which have chosen offsite solutions

Accord Group housing association in the West Midlands is already well practiced at offsite construction – it has produced timber-framed factory built homes since 2011 through its Local Homes division. It currently produces about 200 homes a year with plans to expand significantly. The housing association recently hired a manufacturing expert from Jaguar Land Rover to run the plant – confirming that it's the blend of this timber engineering and manufacturing skill that can best support the housing expertise in local communities.

Liverpool Mutual Homes is building 33 two and three-bedroom homes at Naylorsfield Drive in Liverpool, using timber prefabricated modules manufactured in factory conditions offsite. The modules, manufactured by Bowsall using a timber frame panel system, are transported to site and then craned into place. Designed by JDA Architects, all the homes provide higher than usual energy efficiency to help cut tenants’ fuel bills.

Swan Housing, a housing association in Essex, has chosen to use CLT systems and offsite construction, building homes which are indistinguishable from ones that are built using more traditional methods. Swan is investing £3m in building its own 18,000 sq ft factory in Basildon. It’s designed to provide new homes for the £200m Craylands estate regeneration programme. Their housing modules will be pre-fitted with doors and windows, and once on site the homes are clad and roofed. John Synnuck, Swan's chief executive, says: "At Swan we understand the desperate need for quality new homes. We believe that offsite construction methods will enable us to deliver these much-needed homes quickly, designed to a high specification and with reduced impact on both residents and the environment."